DE 43 09 861 C1 describes a shift arrangement for shifting gears by means of a shift lever. One or two selectively shiftable gears situated on a gearshaft are respectively allocated to a shift plane. Several gears can be shifted by means of the shifting device. At least a gear, or at most two drive wheels, are allocated to a shift plane. Each gear can be shifted only in its predetermined shift plane.
The shift lever is pivotably arranged by means of a support arrangement with respect to a housing. The support arrangement makes possible pivoting movements of the shift lever in a selection plane and in a shift plane aligned transversely of the selection plane. During the selection and shifting processes, the shift lever is guided by a slide.
The shift lever is in a neutral position in the selection plane and is selectively pivotable out of the neutral position into one of at least two inoperative positions in the selection plane by the selection of shift planes. If the shift lever is in one of the inoperative positions, a shift plane is selected. The shift lever is pivotable into a shift position out of the inoperative position in the shift plane for shifting one of the gears. The neutral position of the shift lever is for the most part also one of the inoperative positions, from which one of two gears is selectively shiftable.
In the inoperative positions or in the neutral position of the shift lever, selector shafts are in a middle, neutral position, in which the gears shiftable by means of the selector shafts are not shifted. The shift lever is provided with a shift finger at a free end. Each of the selector shafts has an engagement groove or a shift opening for the engagement of the shift finger. A selective engagement in one of at least two axially parallel selector shafts is effected by selection movements of the shift lever. The shift lever in these positions is movably coupled to one of the selector shafts.
A pivoting of the shift lever in the shift plane from the inoperative position in one or other direction results in a displacement of the selector shaft coupled to the shift lever, since the shift finger acts on a side bounding the engagement groove. One of the gears allocated to the selector shafts is engaged by the displacement of the selector shaft.
The shift lever described in DE 31 25 632 is pivotably received by means of a universal joint with respect to a housing fixed to the vehicle. This joint or this support arrangement provides a box-shaped casing. The casing receives the shift lever and is supported, for pivoting by means of the shift lever, around a tilt axis directed transversely of the pivot axis. The tilt axis is aligned with the middle axis of selectively one or two pivot studs. The pivot studs support the casing, pivotably on the housing in the selection plane, however not in the shift plane. The shift lever is pivotable in the selection plane, immovable in the casing, and pivotable with the casing around the tilt axis. In a selection movement on the shift finger, the shift lever pivoting around the tilt axis takes the casing with it. The shift finger is arranged on the shift lever on the opposite side of the tilt axis from the shift grip (shift knob), and with the shift lever, pivots around the tilt axis in the selection plane.
The support arrangement furthermore provides for a pivotable support of the shift lever in the shift plane around a pivot axis in the casing. The pivot axis runs transversely of the tilt axis. The pivot axis is at the same time the middle axis of a pivot stud arranged in the casing. The shift lever is supported on the casing around the pivot stud in the shift plane, however not in the selection plane. The shift finger is arranged at the opposite end of the shift lever to the pivot axis, also supported pivotably in the shift plane, but not in the selection plane, around the pivot axis. The pivot axis and the tilt axis are situated so that they intersect in a common plane.
This solution, while generally satisfactory, has the disadvantage that because the pivot axis and tilt axis of the shift lever are situated in one plane, limits are set on the adjustment of shift forces and shift paths. “Shift forces” are to be understood as the forces which can be perceptible by the operator on applying force (on shift knob) when the operator selects and shifts gears. The shift lever travels over a path defined on its point of force application when selecting and shifting. Thus each further point on the lever between the point of force application and the pivot or tilt axis travels a path defined by its distance from the axes. The path, for the most part in radian measure, is dependent on the distance of the shift knob to the axes. With the same pivot angle of the shift lever around the tilt axis or pivot axis, each of the points, independently of whether it is swiveled around the tilt axis or pivot axis, travels the same path. The shift lever is frequently guided by a shift slide located between the point of force application and the axes. The design of slides which save material and space is often limited because of the same path of the shift lever in the slide for selection and shift movements. The shift forces on the shift knob can be affected by the lever ratio of the shift lever. The lever ratio results from the distance of the knob from the axes and the distance of the axes from the engagement of the shift finger in the engagement groove of the selector shaft. Limits are as a rule set on the length of the shift lever projecting into the passenger space, conditioned by constructional space. The length of the shift finger, starting from the crossed axes, is dependent on the position of the elements of the internal shift setup adjoining the shift lever.
On selecting the shift plane and on shifting the gears, the pivoting shift lever is guided by means of guide tracks, e.g., a slide. The pivoting movements of the shift lever in the selection and shift directions are limited by stops. The stops ensure that the shift finger after the conclusion of selection engages a shift plane exactly in one of the engagement grooves of one of the selector shafts. The stops which limit the shift path of the shift finger ensure that the selector shaft is displaced exactly into its predetermined position and not beyond it.
Only one gear can be shifted during a shift process. If two gears are allocated to a shift plane, one of the gears in the shift plane cannot be shifted from the outset or is locked in the shift plane by means of a locking device, while the other is shifted. According to the design of the shift device, the further shift planes adjacent to the selected shift plane are locked against inadvertent or automatic selection. A false selection or shift is to be excluded. The gears in the shift planes adjacent to the selected shift plane are locked against inadvertent or automatic shifting during the shift of a gear and when the gear is engaged. The reverse gear is as a rule locked against inadvertent selection or shift from one of the shift positions or selection positions for shift or selection of the forward gears.
Other devices provide for a device for a perceptible increase of the shift force on the shift lever. The device is allocated to the shift plane of the reverse gear. The operator is informed, by means of the markedly rising shift force on selection of the shift plane for the reverse gear, that he is about to engage the reverse gear. The operator's perception of the position of the shift lever relative to the gears is thereby facilitated. The signal given to the operator with increasing selection force is in particular used to warn the operator of inadvertent changing out of a shift plane for the forward gears into the shift plane for the reverse gear. This so-called “crash stop” is effective on inadvertent selection and also on intentional selection of the shift plane for the reverse gear. A brief jump in selection force on the lever signals the change. The selection force is for a moment substantially higher than the forces which occur at the shift knob on selection of the shift planes for the forward gears. After the increased selection force is overcome, the actuating force falls again to a normal level.